The present invention relates to facers for wallboards and methods for making wallboards containing such facers. More specifically, the present invention includes a composite facer for wallboards comprising a nonwoven mat that is adhesively bonded to a scrim fabric reinforcement.
Traditional wallboard contains a cementitious material, such as gypsum or plasterboard, and paper facing on one or both sides thereof. This type of wallboard has various disadvantages. First, the paper facing is generally flammable, which is not usually a desirable quality for wallboards used in building construction. Secondly, if the paper facing gets wet, it tends to peel away from the gypsum or plasterboard core and the structural integrity of the paper decreases, which ultimately allows degradation of the entire wallboard. Further, the paper facing does not impart much strength to the wallboard when wet.
Several attempts have been made to solve these problems. All patents mentioned are hereby incorporated herein by reference in their entirety. U.S. Pat. No. 4,378,405, issued to Pilgrim, discloses a gypsum board having a nonwoven glass fiber tissue embedded in the face of the core and a continuous film of the cementitious material having a higher density and lower porosity than the core extending over the outer face of the tissue. The method for making this product includes the step of vibrating the layer of slurry in contact with the tissue until the slurry penetrates the tissue until it is completely embedded, thus requiring extensive and expensive modification of existing wallboard manufacturing lines.
U.S. Pat. No. 4,810,569, issued to Lehnert et al., discloses a fibrous matfaced gypsum board in which the set gypsum core is sandwiched between two sheets of porous glass mat, with the outer surface of at least one of said mats being substantially free of set gypsum. A disadvantage to this arrangement is that the glass fiber mat is exposed on the outer face of the board, which is an irritant to the skin of workers and others who come into contact with the facing thereof.
International Application Number PCT/NZ98/00105, having International Publication Number WO 99/04112, discloses a reinforced plasterboard having a first layer of paper, a core of a cementitious material, a mesh reinforcement, and adjacent to that mesh reinforcement a further layer of paper. The disadvantages of wallboards having paper facing are outlined above.
Thus, it would be desirable to provide a composite facing material that could be used in place of paper and other facing products to provide a wallboard with superior strength, fire resistance, and water resistance at a reasonable cost. Further, it would be desirable to provide a facing material that may be easily adjusted to conform to various strength requirements. None of the prior art discloses a composite wallboard facing material made from a nonwoven polyester carded mat bonded to a reinforcing laid scrim layer made from continuous glass fibers, which allows a gypsum slurry to penetrate and embed the composite in a face of the wallboard.